Method of forming protective coating on cell safety valve element, cell safety valve element coated with protective film, cell sealing plate using the element, and enclosed cell using the plate

Abstract

A method of forming a protective coating on a cell safety valve element by coating the cell safety valve element with a protective film to protect metal portions thereof against corrosion, a cell safety valve element coated with a protective film, a cell sealing plate using the element, and an enclosed cell using the plate. The safety valve element comprises a coating ( 3 ) obtained by applying an organic paint onto at least one surface of the cell safety valve element ( 10 ) consisting of a metal base plate ( 1 ) having a through hole ( 4 ) drilled therein and a metal foil ( 2 ) laminated on the metal base plate ( 1 ) so as to block the through hole ( 4 ). The sealing plate is formed by bringing the cell safety valve element ( 10 ), on which a protective coating ( 3 ) comprising an organic resin film is formed, into contact with a cell exterior can sealing plate ( 6 ), in which the through hole ( 4 ) acting as a safety valve port is drilled so that the through hole ( 4 ) in the metal base plate of the cell safety valve element ( 10 ) and the through hole ( 7 ) in the sealing plate face each other and bonding the both at a portion around the through hole ( 7 ) in the sealing plate to form the cell sealing plate. The enclosed cell is formed by fitting and supporting the cell sealing plate at the inner periphery of an opening of the cell exterior can in which are housed an electrode body consisting of a positive electrode, a negative electrode and a separator together with an electrolyte to block the opening in the cell exterior can.

What is claimed is:  
     
       1. A method of forming a protection film of a safety valve element for a battery, wherein an organic coating is coated on a safety valve element for a battery comprising a metal substrate having a first hole extending therethrough and a metal foil laminated to said metal substrate so as to cover said first hole after said safety valve element for a battery is applied on a closing plate for a battery container having a second hole extending through said closing plate which is to be a valve opening of a safety valve so that said first hole of said metal substrate of safety valve element for a battery and said second hole of said closing plate are connected through, and said metal substrate and said closing plate are adhered together so that both adhere around said second hole of said closing plate. 
     
     
       2. A method of forming a protection film of a safety valve element for a battery according to  claim 1 , wherein said adhering together of said metal substrates and said closing plate is carried out by laser beam welding. 
     
     
       3. A safety valve element for a battery comprising 
       a metal substrate having a first hole extending therethrough and a metal foil laminated on said metal substrate so as to cover said first hole,  
       wherein a protection film is covered on at least one side of said safety valve element for a battery;  
       wherein said safety element for a battery is applied on a closing plate for a battery container having a second hole extending through said closing plate which is to be a valve opening of a safety valve so that said first hole of said metal substrate of safety valve element for a battery and said second hole of said closing plate are connected through, and said metal substrate and said closing plate are adhered together so that both adhere around said second hole of said closing plate.  
     
     
       4. A closing plate, wherein a safety element for a battery comprising a metal substrate having a first hole extending therethrough and a metal foil laminated on said metal substrate so as to cover said first hole is applied on a closing plate for a battery container having a second hole extending through said closing plate which is to be a valve opening of a safety valve so that said first hole of said metal substrate of safety valve element for a battery and said second hole of said closing plate are connected through, and said metal substrate and said metal closing plate are adhered together so that both adhere around said second hole of said closing plate, and after that an organic coating is coated on said safety valve element for a battery. 
     
     
       5. A closing plate according to  claim 3 , wherein said adhering together of said metal substrates and said closing plate is carried out by laser beam welding. 
     
     
       6. A closing battery, wherein an electrode comprising a positive electrode, a negative electrode and a separator is packed with electrolyte into a battery container and opening portion of said battery container is closed so that said closing plate for battery according to  claim 3  is put into and fixed around inner circumference of said opening portion of said battery container. 
     
     
       7. A closing plate according to  claim 4 , wherein said adhering together of said metal substrates and said closing plate is carried out by laser beam welding. 
     
     
       8. A closed battery, wherein an electrode comprising a positive electrode, a negative electrode and a separator is packed with electrolyte into a battery container and opening portion of said battery container is closed so that said closing plate for battery according to  claim 7  is put into and fixed around inner circumference of said opening portion of said battery container. 
     
     
       9. A closed battery, wherein an electrode comprising a positive electrode, a negative electrode and a separator is packed with electrolyte into a battery container and opening portion of said battery container is closed so that said closing plate for battery according to  claim 4  is put into and fixed around inner circumference of said opening portion of said battery container. 
     
     
       10. A safety valve element for a battery comprising a metal substrate having a first hole extending therethrough and a metal foil laminated on said metal substrate so as to cover said first hole, wherein a protection film is covered on at least one side of said safety valve element for a battery; 
       wherein said protection film is a continuous coated film of an organic coating; and  
       wherein said safety valve element for a battery is applied on a closing plate for a battery container having a second hole extending through said closing plate which is to be a valve opening of a safety valve so that said first hole of said metal substrate of safety valve element for a battery and said second hole of said closing plate are connected through, and said metal substrate and said closing plate are adhered together so that both adhere around said second hole of said closing plate.  
     
     
       11. A safety valve element for a battery comprising a metal substrate having a first hole extending therethrough and a metal foil laminated on said metal substrate so as to cover said first hole, wherein a protection film is covered on at least one side of said safety valve element for a battery; 
       wherein said protecting film is an uncut laminated film of an organic resin film; and  
       wherein said safety valve element for a battery is applied on a closing plate for a battery container having a second hole extending through said closing plate which is to be a valve opening of a safety valve so that said first hole of said metal substrate of safety valve element for a battery and said second hole of said closing plate are connected through, and said metal substrate and said closing plate are adhered together so that both adhere around said second hole of said closing plate.